Pressure regulated volume controlled ventilation versus synchronized intermittent mandatory ventilation in COPD patients suffering from acute respiratory failure

Egyptian Journal of Chest Diseases and Tuberculosis (2016) 65, 121–125

H O S T E D BY

The Egyptian Society of Chest Diseases and Tuberculosis

Egyptian Journal of Chest Diseases and Tuberculosis www.elsevier.com/locate/ejcdt www.sciencedirect.com

ORIGINAL ARTICLE

Pressure regulated volume controlled ventilation versus synchronized intermittent mandatory ventilation in COPD patients suffering from acute respiratory failure Ahmed Abd El-Rahman Ali a, Rabab Abd El-Razik El Wahsh a, Mohammed Abd El-Sattar Agha a, Bishoy Berzy Tawadroos b,* a b

Faculty of Medicine, Menoufia University, Egypt Faculty of Medicine, Menoufia University, 2-Al Saha Street-Quesna-Menoufia, Egypt

Received 11 June 2015; accepted 4 August 2015 Available online 21 August 2015

KEYWORDS Synchronized intermittent mandatory ventilation; Pressure regulated volume controlled; Chronic obstructive pulmonary disease; Respiratory failure; Mechanical ventilation

Abstract Background: Volume controlled ventilation (VC) allows a set tidal volume to be guaranteed but it causes excessive airway pressures that may lead to barotrauma. Pressure controlled ventilation (PC) limits ventilator-induced lung injury but has a disadvantage of variable tidal volume delivery. Pressure-regulated volume controlled ventilation is a kind of dual-control ventilation that combines the advantages of both volume controlled and pressure controlled ventilation. Objective: To compare the pressure regulated volume controlled ventilation (PRVC) versus traditional synchronized intermittent mandatory ventilation (SIMV) in chronic obstructive pulmonary disease (COPD) patients suffering from acute respiratory failure. Patients and methods: This prospective study was carried on 30 COPD patients suffering from acute respiratory failure, divided in two groups: group 1 patients were ventilated using the SIMV mode and group 2 patients were ventilated using the PRVC mode. The arterial blood gas (ABG) parameters, ventilation data, complications and prognosis were compared in the two groups. Results: The ABG parameters improved better in the PRVC group after 6 and 48 h. The peak inspiratory pressure (PIP) values were lower in the PRVC group. There were fewer complications (33% in group 2 versus 86% in group 1). The prognosis was better in PRVC group as 13 patients (86%) were weaned, 1 patient (7%) died and 1 patient (7%) failed to be weaned. On the other hand, 6 patients (40%) were weaned, 3 patients (20%) died and 6 patients (40%) failed to be weaned in the SIMV group.

* Corresponding author. Tel.: +20 1094775499. E-mail address: [email protected] (B.B. Tawadroos). Peer review under responsibility of The Egyptian Society of Chest Diseases and Tuberculosis. http://dx.doi.org/10.1016/j.ejcdt.2015.08.004 0422-7638 Ó 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of The Egyptian Society of Chest Diseases and Tuberculosis. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Ahmed Abd El-Rahman Ali et al. Conclusion: The PRVC mode is better than the volume controlled SIMV mode in ventilating COPD patients with acute exacerbations and type II respiratory failure. Ó 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of The Egyptian Society of Chest Diseases and Tuberculosis. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction The VC ventilation allows a set tidal volume to be guaranteed, but it could bring excessive airway pressures that may lead to barotrauma [1]. Ventilation using a pressure mode may achieve the goals of patient-ventilator synchrony, effective respiratory system support, adequate gas exchange and limited ventilator-induced lung injury, but PC ventilation has a disadvantage of variable tidal volume delivery as pulmonary impedance changes. In recent years, dual-control modes like PRVC have been introduced in an attempt to combine the advantages of volume controlled ventilation with the advantages of pressure controlled ventilation [2,3]. Patients and methods This prospective study was carried out on 30 patients (22 males and 8 females) with acute exacerbations of COPD and type II respiratory failure. The patients were admitted to the intensive care unit (ICU) of the Chest Department, Faculty of Medicine, Menoufia University during the period from May 2013 to December 2014. All other causes of respiratory failure other than COPD exacerbations were excluded from the study. The diagnosis of COPD was made by clinical history, clinical criteria with compatible physical findings, and/or evidence of hyperinflation on the chest radiograph in support with the diagnosis of COPD. Acute exacerbations of COPD were diagnosed regarding the patient’s symptoms (increased dyspnea, increased cough and increased amount of sputum production with change in color, wheezing and chest tightness) [4]. Respiratory failure type II was defined as a partial pressure of oxygen (PaO2) <60 mmHg and/or oxygen saturation (SaO2) <90% with partial pressure of carbon dioxide (PaCO2) >50 mmHg in ABGs measured while breathing room air at sea level [4]. All the patients had undergone full history taking, full examination, ABGs, routine lab investigations, radiology and electrocardiogram. All the patients were intubated and mechanically ventilated. Indications of mechanical ventilation included: severe dyspnea and respiratory distress, respiratory frequency >35 breaths per minute, life-threatening hypoxemia (PaO2 <5.3 kPa, 40 mmHg or PaO2/FiO2 <200 mmHg), severe acidosis (pH <7.25), hypercapnia (PaCO2 >8 kPa, 60 mmHg), respiratory arrest and somnolence or impaired mental status [4]. The patients were randomly divided into 2 groups. The first group was ventilated using the SIMV mode on the Dra¨ger Evita 4 ventilator. The second group was ventilated using the PRVC mode on the Puritan Bennett 840 ventilator. The ventilator parameters were adjusted according to clinical needs, but the specific mode of each group was never changed. Clinical, laboratory and radiological assessments were done for each patient regularly. Frequent ABGS was done. Ventilator data were monitored closely with special focus on peak

inspiratory pressure. Any complications that occurred during mechanical ventilation were recorded and followed up. Weaning process was conducted in 3 steps: Step 1: Asses readiness for weaning Daily screening criteria to assess if the patients were ready for weaning: PaO2 >7.3 kPa (55 mmHg; SaO2 90%) on FiO2 of no more than 30–35%, positive end expiratory pressure (PEEP) <5 cm H2O, PH >7.35 with PaCO2 <50 mmHg, hemodynamic stability as defined by the absence of hypotension and requiring no vasopressors, afebrile, hemoglobin >8–10 mg/dl, adequate mentation, the presence of adequate cough during suctioning, stable metabolic status (e.g., acceptable electrolytes, proteins) and resolution of disease acute phase [5]. Step 2: Invasive continuous positive airway pressure (CPAP) plus pressure support If the patient seemed ready for weaning, the next step was to give a short trial of spontaneous breathing by using invasive CPAP plus pressure support without any mandatory breaths. Pressure was titrated to achieve a tidal volume (VT) of more than 5 ml per kilogram of body weight and a frequency of <25 breaths per minute. The pressure support was decreased gradually to 8 cm H2O. Those who failed were reassigned to the SIMV mode or PRVC mode according to the group. Trials of spontaneous breathing lasted for 2 h [6]. Step 3: Extubation Patients who tolerated pressure support <8 cm H2O for two hours with no apparent signs of distress were extubated. During the first 24–48 h after extubation, noninvasive ventilation (bi-level positive airway pressure mode) was delivered until it was tolerated 20–22 h per day. The level of inspiratory positive airway pressure (IPAP) was decreased by 2 or 4 cm H2O per day in patients with good tolerance; patients were allowed to breathe spontaneously. Weaning failure was defined as the failure to pass a spontaneous-breathing trial or the need for reintubation within 48 h following extubation [7]. Results The study was carried out on 30 COPD patients, the mean age of the SIMV group was (63.47 ± 4.78) years and the PRVC group was (63.93 ± 4.98) years. There was no significant difference between the two groups regarding demographic data, clinical presentation, ABG parameters, radiological and laboratory findings prior to ICU admission. The results of this study showed that the peak inspiratory pressure values (after 24 h of intubation and before extuba-

Pressure regulated volume controlled ventillation In COPD patients

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Comparison between the PIP values and duration of ventilation in SIMV and PRVC groups.

Table 1

Ventilation data

Studied groups SIMV group (n = 15) No.

Test of significance

P value

PRVC group (n = 15) %

No.

%

PIP after 24 h of intubation (cm H2O) 40–45 10 35–40 5 30–35 0

66.7 33.3 0

4 0 11

26.7 0 73.3

v2 = 18.57

<0.001 HS

PIP before extubation (cm H2O) 30–35 4 25–30 11 20–25 0 15–20 0

26.7 73.3 0 0

0 0 2 13

0 0 13.3 86.7

v2 = 30.00

<0.001 HS

t = 7.80

<0.001 HS

Duration of ventilation (days) Mean ± SD 9.80 ± 2.11

5.07 ± 1.03 2

PIP = peak inspiratory pressure, SD = standard deviation, HS = highly significant, (v ) = Chi-squared test, t = student’s t-test, h = hour, n = number.

80 70

73.3 66.7

60

%

50 40

Group I

33.3

Group II

26.7

30

Discussion

20 10

0

0

40-45

35-40

0 30-35

Figure 1 Comparison between PIP values after 24 h of intubation among SIMV and PRVC groups.

tion) and the duration of ventilation were significantly reduced in the PRVC group (Table 1 and Fig. 1). The results of this study showed that the ABG parameters improved faster and better after 6 h and 48 h of ventilation in the PRVC group (Tables 2 and 3).

Table 2

The results of this study showed fewer complications and better prognosis in the PRVC group. The patients in the SIMV group encountered complications related to ventilation like VAP and pneumothorax (Tables 4 and 5 and Fig. 2). The weaning success was higher in the PRVC group as 13 patients (86%) were weaned successfully versus 6 patients (40%) in the SIMV group. The survival ratio was better in the PRVC group (Table 5).

Pressure-regulated volume controlled ventilation, also known as adaptive volume control plus (VC+), is a kind of dualcontrol ventilation that uses tidal volume as a feedback control for continuously adjusting the pressure limit [3]. In this study, we found a shorter duration of ventilation and lower PIP values with PRVC ventilation in comparison with SIMV (Table 1 and Fig. 1). This agreed with Alvarez et al. [8] who compared volume-controlled ventilation, pressure-limited time-cycled ventilation, and PRVC in 10 adult patients with acute respiratory failure and reported that PRVC resulted in a lower peak airway pressure compared to VC ventilation. Also, Sachdev et al. [9] found a significant reduction in PIP of 19% when the ventilation mode was changed from VC

Comparison between ABG parameters after 6 h of intubation in SIMV and PRVC groups.

ABG after 6 h of intubation

PH PCO2 (mm Hg) PO2 (mm Hg) SO2 % HCO3 (meq/l)

Studied groups SIMV group (n = 15) Mean ± SD

PRVC group (n = 15) Mean ± SD

7.29 ± 0.02 65.53 ± 3.48 54.47 ± 3.64 84.80 ± 3.76 31.16 ± 3.52

7.36 ± 0.02 52.00 ± 3.54 73.60 ± 9.50 93.57 ± 4.37 29.53 ± 1.41

Student’s t-test

P value

9.59 10.35 7.28 5.89 1.66

<0.001 HS <0.001 HS <0.001 HS <0.001 HS >0.05 NS

PCO2 = partial pressure of carbon dioxide, PO2 = partial pressure of oxygen, SO2 = oxygen saturation, HCO3 = bicarbonate, HS = highly significant, h = hour, SD = standard deviation, n = number.

124 Table 3

Ahmed Abd El-Rahman Ali et al. Comparison between ABG parameters after 48 h of intubation in SIMV and PRVC groups.

ABG after 48 h of intubation

Studied groups

PH PCO2 (mm Hg) PO2 (mm Hg) SO2 % HCO3 (meq/l)

SIMV group (n = 15) Mean ± SD

PRVC group (n = 15) Mean ± SD

7.30 ± 0.04 58.20 ± 3.74 63.13 ± 4.68 91.40 ± 2.23 32.83 ± 5.09

7.39 ± 0.03 46.93 ± 2.71 71.27 ± 5.86 93.47 ± 1.55 30.13 ± 3.09

Student’s t-test

P value

6.40 9.45 4.19 2.95 1.76

<0.001 HS <0.001 HS <0.001 HS <0.05 S >0.05 NS

PCO2 = partial pressure of carbon dioxide, PO2 = partial pressure of oxygen, SO2 = oxygen saturation, HCO3 = bicarbonate, HS = highly significant, S = significant, n = number, SD = standard deviation.

Table 4 Comparison between complications in the SIMV and PRVC groups. Complications

Present Absent

Studied groups

Fisher’s exact test

P value

SIMV group (n = 15)

PRVC group (n = 15)

No.

%

No.

%

13 2

86.7 13.3

5 10

33.3 66.7

8.89

<0.05 S

20 20 20 20 0 20

Z test 0.09 0.19 0.09 0.09 0.77 0.09

>0.05 NS >0.05 NS >0.05 NS >0.05 NS >0.05 NS >0.05 NS

Type of complications Septic shock 1 VAP 5 Hematemesis 1 UTI 1 Pneumothorax 4 Arrthymia 1

if present 7.7 1 38.5 1 7.7 1 7.7 1 30.7 0 7.7 1

VAP = ventilator associated pneumonia, UTI = urinary tract infection, n = number, S = significant, NS = non-significant.

to PRVC while inspiratory time, respiratory rate, and FiO2 were kept constant. In agreement with our study, Rappaport et al. [10] reported a shorter duration of ventilation when pressure limited mode (decelerating flow) was compared with VC ventilation in adults. This was in contrary with Guldager et al. [11] who found that the PRVC mode didn’t shorten the duration of mechanical ventilation.

The results of the present work showed that there was a highly significant difference between the two groups regarding PH, PCO2, PO2, and SO2 in the ABG after 6 h and 48 h of mechanical ventilation (Tables 2 and 3). In agreement with results of this study, Sachdev et al. [9] concluded that PRVC had improved oxygenation with improvement of PaO2 and PaO2/FiO2 in the initial stages of ventilation. Abou Shehata et al. [12] also found that there was a significant improvement of arterial blood gases after 1 h, 2 h, 2nd day and 3rd day of using PRVC. This was in agreement with Tiruvoipati et al. [13] who concluded that PaCO2 decreased significantly after PRVC than volume-controlled ventilation (SIMV). The results of this work were in contrary with the results of Piotrowski et al. [14] who compared the use of patient triggered PRVC and intermittent ventilation in neonates in a prospective randomized study and did not find any difference in oxygenation status. The results of this study showed that there were fewer complications and better prognosis in the PRVC group rather than the SIMV group (Fig. 2). The incidence of VAP in group 1 was 38.5% while it was 20% in group 2 (Table 5). This was in agreement with Marin et al. [15] who studied 314 patients admitted to the ICU and required MV for more than 5 days 38.5

40 35

30.7

30

Table 5 groups.

Comparison between prognosis in SIMV and PRVC

Prognosis

Weaned Died Failure of weaning

%

25 20

20

20

20

20

20 Group I

15

v2 test

Studied groups SIMV group (n = 15)

PRVC group (n = 15)

No.

%

No.

%

6 3 6

40 20 40

13 1 1

86.6 6.7 6.7

P value

10

Group II 7.7

7.7

7.7

7.7

5 0

7.12

n = number, (v2) = Chi-squared test, S = significant.

0

<0.05 S

Figure 2 Comparison between complications in SIMV and PRVC groups.

Pressure regulated volume controlled ventillation In COPD patients and reported that 34 (39.1%) patients with late-onset VAP died during hospitalization. There was a higher incidence of pneumothorax in the SIMV group (30%) than the PRVC group (0%) (Table 4). This was in agreement with the study of Delassence et al. [16] who reported that peak airway pressure over 50 cm H2O is associated with increased risk of alveolar rupture during mechanical ventilation. They found a correlation between high peak airway pressure and the development of the pneumothorax. Also, Parker et al. [17] suggested in their study that increased duration of the high PIP and resultant alveolar overdistension is probably associated with pneumothorax. In contrary to the results of the present study, Sachdev et al. [9] found that occurrence of ventilation-related complications such as pneumothorax or pneumonia was not found to be different in PRVC or VC groups. In this study, 86% of patients in the PRVC group were weaned successfully versus 40% in the SIMV mode (Table 5). This was in agreement with Lellouche et al. [18] who tried the PRVC mode and found less clinician intervention and faster weaning. In this study, the survival rate after ventilation by the PRVC mode was 92% versus 80% after ventilation by the SIMV mode. However, half of the survived patients in group 1 failed to be weaned as a result of complications (Table 5). In agreement to this study, El-Shafey et al. [19] found 86.66% survival in COPD patients with respiratory failure on the PRVC mode. In contrary to this study, Abou Shehata et al. [12] found that there was no significant difference in the outcome of PRVC as regards survival between different etiologies of respiratory failure. This was in contrary to the result of Guldager et al. [11] who found 54.54% survival after PRVC ventilation. However, the last two studies used PRVC in acute respiratory failure of different etiologies and not COPD only like that in our study. Conclusion The PRVC mode is better than the volume controlled SIMV mode in ventilating COPD patients with acute exacerbations and type II respiratory failure. The PRVC mode showed faster improvement, shorter ICU stay, fewer complications and lower peak inspiratory airway pressures. Weaning of patients on the PRVC mode was easier than that on the SIMV mode and the prognosis was better with a lower mortality rate in the PRVC group. References [1] J.W. Sohn, Y.S. Koh, C.M. Lim, et al, The usefulness of pressure-regulated volume control (PRVC) mode in mechanically ventilated patients with unstable respiratory mechanics, Tuber. Respir. Dis. 44 (6) (1997) 1318–1325.

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